This invention relates generally to image scanners. More specifically, the present invention relates to motorized movement of hand held scanners.
Generally, hand held scanners contain a light source, a reflective element, a lens assembly, a detector array, and a set of rollers facilitating movement over an image to be scanned. In operation, the light source emits light onto the image. The light scattered from the image is reflected by the reflector and then focussed through the lens assembly onto the detector array. The detector array scans a single line at a time requiring continuous repositioning of the entire scanner in order to scan the entire image. Typically an operator manually moves the scanner over the image, which sometimes results in image scanner errors. Typical causes of errors include: (i) erratic hand movements due to shaking; (ii) varying scan speeds; (iii) movement which does not follow a straight vertical line along the paper; and (iv) the inability to maintain low speed during high resolution scans.
A motorized scanner can alleviate the above problems. Most motorized scanners are large desk-top size devices in which the image to be scanned is held stationary, and the entire light/reflector/detector assembly is moved, similar to a copying machine. Although such a device reduces image scanner errors, it lacks portability and is often more expensive than hand held scanners.
One device that combines the benefits of the hand held scanner with those of the desk-top scanner is shown in Taiwan Utility Model Application No. 80212207. Two embodiments of the invention are shown. In the first embodiment, a power box containing a motor and gear assembly is manually brought into contact with the scanner's rollers. In the second embodiment, a "float gear" resides between the power box and the roller assembly. Under manual operation, the power box gear assembly is at rest and the rotation of the rollers does not cause the engagement of the float gear. In automatic operation, the power box assembly rotates, causing the float gear to engage the roller assembly.